Corrigendum: Enhancing enzyme-mediated cellulose hydrolysis by incorporating acid groups onto the lignin during biomass pretreatment - Jie Wu; Richard P. Chandra; Masatsugu Takada; Masatsugu Takada; Li-Yang Liu; Scott Renneckar; Kwang Ho Kim; Chang Soo Kim; Jack N. Saddler (Frontiers in Bioengineering and Biotechnology)